The proposed study builds on the well documented Chronic Care Model (CCM) and prior mental health- primary care collaborative care approaches to suggest a new approach to meeting the mental health needs of homeless mothers. The new Integrated Care Model for Homeless Mothers (ICMHM) addresses some of the shortcoming of the CCM and prior collaborative care models to overcome aspects that are less effective for highly vulnerable populations. These include: 1) a single disease focus; 2) failure to address basic needs that may limit treatment adherence; 3) assumption that patients are motivated about treatment needs; and 4) provision of self management recommendations without recognition of limited resources. The proposed study will use the prior evidence for Chronic Care Model and depression treatment systems in primary care, combined with the study team's already successfully tested innovations managing depression, substance use and other co-morbid mental health conditions, with poor and transient populations, to demonstrate how a new model of integrated care, the ICMHM, can meet the mental health needs of homeless mothers with depression. Targeting homeless mothers is important because they comprise the fastest growing segment of the homeless population and are a vulnerable group that has had little engagement with mental health services, despite a high prevalence of depression, and co-occurring anxiety and substance abuse. These issues interfere with their ability to care for their children, maintain housing, and successfully pursue employment and education. Further, no treatment studies targeted to homeless mothers with depression have been rigorously tested in the literature. We propose to implement and test the new model in a quasi- experimental design using Health Care for the Homeless clinical sites in New York City, targeting homeless female heads of household with depression. Proposed study goals are to: 1) examine the efficacy of the ICMHM for homeless mothers with depression and other mental health and substance use issues in improving depression, substance use, and physical and mental health functioning; 2) document feasibility for a larger scale RCT to establish the efficacy of the ICMHM for improving depression, mental and physical health functioning, substance use, and housing and other functional outcomes; and 3) determine individual and program factors that moderate outcomes of the ICMHM. Demonstration of the success of this new model can affect health care delivery in the 180 Health Care for the Homeless sites across the country. PUBLIC HEALTH RELEVANCE: The proposed study will use elements of the evidence-based Chronic Care Model, and studies of prior depression in primary care collaborative models, combined with the study team's already successfully tested innovations managing depression, substance use and other co-morbid mental health conditions, with poor and transient populations, to demonstrate how a new model of integrated care, the Integrated Care Model for Homeless Mothers (ICMHM) can meet the mental health needs of homeless mothers with depression. It will provide critical information that points clinicians and policymakers toward better ways to address the complex needs of a highly at-risk population in the primary care setting.